Spray gun apparatus



v March 15, 1949. MEYERS SPRAY GUN APPARATUS 2 Sheets-Sheet 1 Filed Feb. 19, 1945 IINVENTOR GeorgeN.Meyers WW ATTORNEY March 15, 1949. G. N. MEYERS 4 2,464,764

SPRAY GUN APPARATUS Filed Feb. 19, 1945 2 Sheets-Sheet 2 lIIlIIIIIIIIIIIIIIIIIIII/lfi IIIIIIIIIIIA'IIIIIIIIIIIIA INVENTOR GeorgeNMeyers.

W Fr

. ATTORNEY Patented Mar. 15, 1949 V. 1 i This invention relates to spray gun apparatus for the application of paint, rust preventives :andthe like, to either external or internal sur- ;i aces.-

Among the objects of .the invention, are to pro- -v-ide a spray gun apparatus which is particularly useful and efficient in conjunction with the sprayf l g of internal areas such as a metal tube. An- ;otherobject is the provision of spray gun apparatus which eliminates permanent disposition ,oflsolidified spray material in areas adjacent the spray nozzle and external to the surfaces being treated. Still another object is the provision of an effective seal between the spray nozzle and the connections to the workpiece. An object also isthe provision of a spray gun connection which lis susceptible to easy pivotal movement without developing breakdown of the connections. Ad- ".Iditio'nal objects of the invention relate to the utilization of efiicient recovery means for unused spray material, to electric circuit means for con- ;f trolling the time of spray, to spray shield means for the workpiece and to other details of the asfllsembly and arrangement which will appear on "consideration of the following detailed descrip- ",tion and accompanying drawings. In the drawings, which illustrate preferred embodiments and -iphysica1 arrangements of the invention,

Figure 1 is a view, partly in section, showing I the apparatus in association with workpieces being treated; If g Figure 2 is a detail of the spray gun units as irelated to the vacuum chamber and workpiece;

Figure 3 is a diagrammatic showing of the elecfitri'c circuit; and

Figure 4 is a detail showing of a modification of the spray shield apparatus.

The apparatus as shown in Figure 1 is intended ffor the spraying of the internal surfaces of a bomb shell, although applicable to any closed ll interior surface. As shown, the shells I are flinou'nted on shield tubes 2 provided with base ffsupports 3 on which the lower edges of the shells f loosely rest. The dimensions of the shield tubes ""2 are such as to provide a relatively close fit to ithe workpieces, difierent tubes being usable for different workpieces, as required. The base supports 3 are fixed to the upper surface of a vacuum chamber or box 4 formed of an upper fiat plate 5 containing apertures 6 in the area aligning :ffwlth the tubes 2, and a lower plate I having secfl tions converging from the box edge to th center llwhere an opening 8 is formed. An outlet pipe "9 is screw threaded to the edge of this opening.

, As shown, the edge of the box 4 is continuous.

" omreofsrArE-s George N. Meyers, Audubon, N. J., assignor to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania Application February 19, 1945, Serial No. 578,574

' 4 Claims. (01. 91-45) the end extensions 'of the adjacent straps.

PATENT. OFFICE with the upper plate 5 and forms with the lower plate I, an air sealed chamber by means of the edge strip 9 of rubber or rubber-like composition against which the box edge is held by means of bolts I0 passing through both plates. A pin hole aperture II is provided through a screw-I2 or lugs I6 and IT. A third and U-shaped strap I8 having end lugs I9. and 20 is adapted for attachment in extension of the pair of straps l4 and I5, connection being made by machine bolts 2I and 22 passing through apertures formed in The cross piece 23 of the end strap I8 is bifurcated so as to receive the adjusting terminal 24 of the spray gun 25, when this gun is positioned between ithe straps I4 and I5, and the nozzle 26 thereof extends through the opening I3 formed "in the base plate I of the vacuum box 4. A taper washer '21 is'fixed by welding or other meansto the inner surface of base plate 1 directly over the aperture I3. The inner edge 28 of the washer is tapered to correspond approximately to the tapered surface 29 formed on the spray end'of the gun nozzle 26 and intermediate the nozzle and washer, a gasket 30 of yiel-dable and airproof material, such as rubber or the like, is interposed so as to form an efiective seal for liquid, 'air'gor other gases.

It is pointed out that the lug pairs I6I1 and I9-2U are, when the spray gun is placed in position with th nozzle in contact with the,

gasket 30, spaced from each other so that a degree of adjustment by means of the bolts 2I and 22 may be obtained as desired. Also the openings formed in the lugs I9 and 20 of the lower strap I8 have a diameter in excess of that of the bolts so that the strap may be shifted laterally to cause a virtual pivoting of the gun. This may take place inasmuch as the gasket 30 at the gun nozzle yields to permit a shifting in the lateral position of the gun.

nection 4I admits under control of valve 43, air

un e Pr s r r rl- Pipe 4 -fil a" ward the outlet pipe 9.

and gage are provided in this inlet connection. Pipe connection 42 leads directly to the spray guns 28 through branch pipes 41 and 48. From the air inlet 44 connection is also made to the guns through the pipe 49 and branch pipes and 5!, air pressure control in this airline is obtained through the manually adjusted automatic air pressure regulator 52, the period during which air flows being automatically controlled by solenoid valve 53. An air pressure gage 54 is also provided. Additionally, pipe extends from the source pipe 44 controlled by manual valve 56 to the vacuum box 4, the connect-ion passing through an opening in the top plate 5 or any other convenient opening as desired, and into the outlet tube 9, where it terminates at a point short of the end of this tube. Directly beneath the end of outlet tube 9 is placed a waste receptacle 58.

From the description of the apparatus to this point, the general functioning of the same may be apparent. When air under pressure is introduced to pipe 4|, paint or other coating material is forced through pipe 42 and branches 4'! and 48 to the air guns 28, the pressure being adjusted to lift the liquid to a point short of the nozzle end. Impetus and effective spray formation is supplied to this air-paint stream by the air supply through pipe 49 and branch pipes 48 and 5 I, sending the mixture in a rapid stream through the vacuum box 4 and shield tubes 2 into the area of the shells l above the tubes.

If no other apparatus were supplied, the spray operation would be a failure from the practical viewpoint inasmuch as the spray stream is received in a closed space and dead air regions prevent the desired disposition of the spray material to the surfaces being treated. To overcome this difficulty, the vacuum box 4 with the associated air pressure line 55 is provided. When valve 56 is opened and air current flows from pipe 55 through outlet pipe 9, the moving air stream draws air from the interior of the sealed box 4 as indicated by the arrows. If this air stream flows continuously, therefore, the pressure within the box 4 will be continuously sub-atmospheric. Also by reason of the pin hole openings H a continuous trend of air is developed from the box edges toward the outlet pipe 9. The effect of this reduced pressure in the box is to produce an air movement from the loose junction between the base nut 3 and shell I, between the shell and tube 2 and down through the interior of tubes 2 to- Thus the pressure within the shell spaces is sub-atmospheric and as a consequence the spray stream readily passes upwardly through the tubes 3 and into the shell space where it deposits the spray material over the entire surface above the tube ends.

By reason of the pin hole opening II and the consequent continuous movement of air toward the outlet pipe 9, any condensation of spray on the base plate of box I is drawn toward the outlet pipe. This movement is accentuated by the inclination of the base plate toward the outlet pipe. Thus any tendency of the spray material to accumulate and solidify, requiring more or less frequent removal, is obviated.

In order to secure efficient handling of the spray material, given the apparatus as described, it is important that the spray be applied for a predetermined limited time period. In Figure 3 is shown a time control circuit for the solenoid valve 53 indicated in the pipe line 49 of Figure 1. In this diagram a source of alternating current is indicated by the numeral 58. From this source through the manual switch 6| and fuses 62, current is led to the transformer 53. From the secondary of this transformer connection is made to the relay coil 64 by way of conductors B5 and 6B, dependent upon the closure of initiating switch 85. On closure of switch 85 current passes through conductor 65, relay coil 54, time delay switch 61, conductors 68 and 69, switch 85 and conductors l8 and II. This energizes relay 64 and operates its switch 12, having contact arms 13, 14 and 15, closing the same. Closure of contact l3 establishes a holding circuit from conductor 68 through conductor 16, TI and II to the transformer 83, by-passing initiating switch 85 which may then be opened. Closures of contacts 14 and 15, with manual switch 18 closed, energizes solenoid coil 53a, causing the beginning of the spray cycle in the apparatus.

Closure of initiating switch 85 also energizes the time delay relay coil 19 which, after a predetermined time period operates to open the time delay relay switch 61. As in the case of relay 64, relay switch 12 functions to hold the energizing circuit through relay 19 after switch 85 is opened. On opening of time delay switch 61, relay switches 14, 15 are opened, breaking the circuit through solenoid coil 53a. and stopping the spray cycle. Hence, the entire cycle is accomplished merely by closing the initiating switch 85 and opening it again at will, the spray cycle being controlled by the time delay relay l9 and the automatic relay switch, connections for the solenoid coil 53a. being controlled by relay coil 64.

As previously indicated, the shield 2 as employed for interior spraying, may be changed as to length, to vary the extent of spray surface within the workpiece. In some cases it may be desirable to spray the Whole interior surface with paint, with the exception of a threaded section adjacent the open end of the shield. This threaded section preferably should be sprayed with rust resisting composition and this may be accomplished by use of the shield and supporting unit shown in Figure 4. In this unit the workpiece 80 is mounted directly on the upper plate 5 of the vacuum box 4, or upon the ends of support rods 8| which are fastened by an appropriate means to the plate 5. The other ends of the sup-- port rods 8| are fixed to an inverted conical shield 82 the apex of the shield being centrally positioned at the plate aperture 6 and the skirt edge of the cone lying adjacent the approximate inner surface of the workpiece when in position. A guide and retaining ring 83 is also fixed to the plate 5 surrounding the shield 82 for supporting the workpiece in proper relationship to the shield.

In the action of this particular type of shield, the spray from the nozzle gun impinges on the conical surface of the shield and is deflected toward the threaded section of the workpiece to coat the same. The down coming draft of air around the edges of the shield tend to prevent penetration into the upper space of the workpiece interior above the shield. This draft is due to the sub-atmospheric pressuremaintained-in the vacuum chamber as herein above described.

While emphasis has been made on spraying of interior surfaces the apparatus may be also employed for exterior coating. This may be accomplished by placing the guns at edge apertures of the vacuum box and extending the workpiece through the top plate of the box within range of the gun spray.

Modifications of the invention, other than as herein referred to, may be made and hence no limitations arising from the specific disclosure are intended other than may be required by the claims hereto appended.

What is claimed is:

1. In spray gun apparatus, a work receiving sup port, a spray gun having a nozzle, a sub-atmospheric pressure chamber between said support and nozzle, and connection means between the nozzle and chamber permitting pivotal shifting of said gun, said connection means comprising a yieldable annular plate surrounding an opening in the chamber wall and forming a sealing contact with said nozzle through which the out let portion of the nozzle projects.

2. In spray gun apparatus, a work receiving support, a spray gun having a conical nozzle, 2. subatmospheric pressure chamber between said support and nozzle, and connection means between the nozzle and chamber, said connection means comprising an annular yieldable plate having inclined inner edges corresponding to the conical nozzle surface, said plate being positioned around an opening in the chamber and forming a sealing contact with the plate through which the outlet portion of the nozzle projects.

3. In spray gun apparatus, a work receiving support, a spray gun having a nozzle, a sub-atmospheric pressure chamber between said support and nozzle, and connection means between the nozzle and chamber permitting pivotal shifting of said gun, said connection means comprising a yieldable annular plate inside said chamber and surrounding an opening in the chamber wall through which the outlet portion of the nozzle extends into sealing contact with said plate.

4. Spray gun apparatus comprising an enclosed chamber, a spray gun mounted to project the spray toward and through an opening in one wall of th chamber and having a substantially airtight joint with said wall, a work holder positioned to hold the work to receive spray through an opening in an opposite wall of the chamber, said work holder, with a workpiece in place, forming a substantially air-tight closure over said opening in said opposite wall, means for withdrawing air from the chamber to create a subatmospheric pressure therein, and a restricted opening in a wall of said chamber for admitting a limited amount of air, said opening being located in such position that air entering the chamber therefrom passes over and across the inner end of the spray gun.

GEORGE N. MEYERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

